Myocardial signal intensity decay after gadolinium injection: a fast and effective method for the diagnosis of cardiac amyloidosis

Late Gadolinium Enhancement (LGE) pattern of cardiac amyloidosis (CA) at cardiac magnetic resonance (CMR) examination is absent in approximately 30 % of patients. We tested whether the evaluation of myocardial gadolinium signal intensity (SI) decay (SID) has a higher diagnostic accuracy for CA. CMR was performed in 59 patients with systemic AL amyloidosis (36 males, 69 ± 10 years, mean ± SD), and 20 age/sex-matched healthy controls. LGE images were acquired every minute up to 8 min after gadolinium injection (time of inversion 250 ms). SI regions of interest were plotted in SI/time curves for endocardial (Endo) and epicardial layer of interventricular septum, cavity, and skeletal muscle as reference. SID (a negative exponential function described by the parameter T_SID) was expressed as number of heart beats (HB) from each ROI. The typical LGE pattern for CA was detected in 42 patients (Ty-LGE), while 17 showed either absent LGE or an atypical pattern (ATy-LGE). A definite CA diagnosis was confirmed in all Ty-LGE patients and in 10/17 ATy-LGE patients. At ROC analysis Endo-T_SID was the most accurate parameter to distinguish Ty-LGE and ATy-LGE patients from controls. A 269 HB threshold (mean + 2 SD Endo-T_SID measured in controls) identified 51/52 patients with definite CA diagnosis, with 98 % sensitivity, 93 % specificity, and 96 % diagnostic accuracy. A direct relation was found between the extracellular volume and Endo-T_SID in CA patients (r 0.72, 95 % CI 0.37–089, p < 0.001). the analysis of myocardial SID after gadolinium injection improves the accuracy of CMR for CA diagnosis.